Hydronix CB-25-1005 NSF Carbon Block Filter 2.5" OD X 9 7/8" Length, 5 Micron 5 micron carbon block for higher chlorine reduction than granular activated carbon (GAC) or powdered activated carbon (PAC) Coconut carbon block for better tasting water than traditional GAC or PAC filters Improves unpleasant taste and odor issues Combines high purity standards with multifunctional versatility in one cartridge